Optical power loss measurements are crucial for proper management of network communication systems. To this end, the Telecommunications Industry Association (TIA) and the American National Standards Institute (ANSI) established standard procedures for measuring power loss values using a light source and a power meter (referred to as the Light Source Power Meter (LSPM) approach). The ANSI/TIA-526-14-B-2010 Standard proposes different methods for referencing an optical power loss measurement (OPLM) system based on the LSPM approach. These referencing and measuring procedures were thus meant to standardize optical power loss measurements associated with a multitude of scenarios that are expected to occur in this field.
The one-cord reference procedure described therein (see Annex A) for instance provides insertion loss measurements having minimized uncertainty and includes insertion losses associated with both end connectors of the DUT. However, the one-cord reference procedure requires that the power meter employs a large-area detector. Conversely, the three-cord reference procedure described therein excludes losses associated with both of the end connectors whereas the two-cord reference procedure includes the loss of one of the end connectors. Both the three-cord and the two-cord reference procedures may be employed with fiber-pigtailed detectors but they are known to introduce a small bias in the insertion loss measurement (see ANSI/TIA-526-14-B-2010 B.5 and C.5).
Multifunction OLTSs, such as the FOT-930 test instruments manufactured by EXFO Inc., are handheld devices that provide insertion loss measurements based on the LSPM approach, which conveniently incorporate measurement of additional parameters such as bi-directional Optical Return Loss (ORL) measurements and fiber-length measurements. However, because the OLTS power detectors are fiber pigtailed, the one-cord reference procedure is not applicable and the two-cord and/or the three-cord reference procedures may suffer from the aforementioned small bias.
Although existing OPLM techniques are satisfactory to a certain degree, it would be desirable to overcome their limitations with an improved measurement technique.